Stroke is the third largest cause of death and the number one cause of serious disability in the United States. New methods are being sought to limit the amount of neuronal damage that occurs in patients who have had an acute stroke. One of these methods is with a group of drugs that are antagonists of the N-methyl-Daspartate (NMDA) receptor. Licostinel is a selective NMDA antagonist that appears to produce fewer central nervous system side effects than previously tested agents. The principal objective of this study is to determine the effects of probenecid on the pharmacokinetic profile of licostinel. We also seek to determine the effects of licostinel when administered alone or in combination with probenecid on renal function and venous inflammation at the site of licostinel administration. Our expectation is that probenecid will markedly prolong the half life of licostinel and reduce the amount of licostinel that is excreted by the kidneys. Information obtained during this study of 18 patients will be used to plan more definitive studies and seek to determine an optimal route of licostinel administration.